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Options

In addition to our wavelength meters for standard-, UV- and IR-measurement range, several options are avialable. The flexible design of the wavelength meters permits the integration of additional optical components and software modules, allowing custom solutions for customer specific applications. Standard options include:

Linewidth option - L
Diffraction grating option - D
Double-pulse option - DP
Multi channel switcher (up to eight channels) - MC
External TTL trigger option - TTL
Lasercontrol output with PID-controller - PID

Linewidth Option - L

Linewidth measurement of a single mode laser source is performed by a special algorithm which eliminates interferometer apparatus function. The algorithm enables the measurement of the linewidth several times better than the interferometer resolution. With multimode lasers or lasers with sidebands, the value is interpreted as FWHM of their envelope function. The longitudinal mode splitting needs to be less than 300 MHz.

Diffraction Grating Option - D

The Grating option allows the analysis of the spectrum with an accuracy of 0.02 nm. This is applicable to laser sources with broad emission.
The grating option is available for WS5 and WS6 only.

Double-Pulse Option - DP

Simultaneous measurement of two laser wavelengths

The double-pulse option allows the measurement of two almost simultaneous laser pulses. Timing gates of at least 400 ns are applied and the emission of the two lasers is monitored. The double-pulse option supports pump and probe experiments.

Multi Channel Switcher - MC

Multi Channel wavelength meter for up to 8 fiber inputs

The combination of our high-speed wavelength meter with one of the quickest fiber switchers allows the measurement of up to 8 channels almost simultaniously (< 0.3 s /8 channels). The switcher is controlled by our wavelength meter software via RS232, exposure time can be set for each channel independently. Spectral range: 280 nm - 2200 nm, lifetime: > 5*10⁸ cycles.

For this option in the delivery is included additionally:
External switcher box
RS232-connection cable (switcher - computer)
Power supply for the switcher
1x 50 µm multimode fiber

External TTL trigger option - TTL

This option allows the user to trigger pulsed measurements externally. It guarantees synchronization between pulsed excitation and measurement. It gains low-noise and pollution-free signals on measuring pulsed signals with low duty cycles. There are two different ways to trigger:

In mode 1 the TTL-pulses are used to start and stop the measurement. The TTL-pulse triggers the read-out of the arrays. Afterwards the CCD-arrays are illuminated until the next TTL-pulse is detected. In this mode, the illumination is given by the TTL-pulse distances and therefore cannot be set by the program.

Mode 2 triggers the measurement start. After the TTL-pulse and a security period of ~ 10 µs, the sensors are illuminated for a user-defined period of time (integration time ~1 - 10 ms). The laser pulse must not occur within the security zone!

For this option in the delivery is included additionally:
LEMO-cable, -BNC-adaptor and -connector

Lasercontrol output with PID-controller - PID

The PID-option is based on the Lasercontrol option. The PID-option now provides the possibility to keep the laser frequency fixed (like the LC-option) and even to let the frequency follow any arbitrary mathematic function, e.g. sine, triangle, rectangle, heavyside, etc. and any combination of them.

Combination of a triangle- and sine-modulation of a DFB-laserdiode running at 780 nm:

The regulation of the frequency is done by a Proportional-Integral-Derivative controller. The basic idea is that the controller reads the actual frequency. Then it subtracts the measurement from a desired "setpoint" to determine an "error". The error then is treated in three different ways simultaneously:

 To handle the present, the error is multiplied by a proportional constant P. P is always negative, to drive the output toward the setpoint.

 To handle the past, the error is integrated over a period of time, and then multiplied by a constant I.

 To handle the future, the first derivative of the error (its rate of change) is calculated with respect to time, and multiplied by another constant D.

The principal function for a PID controller is:

The single parameters of the proportional (P), integral (I) and derivative (D) part can be set independently as well as the total sensitivity (V/nm).

Settings of PID-controller and sensitivity

This option is very useful in experiments, where the laser frequency has to fit changing experimential conditions, like laser cooling, atomic manipulation and detection, raman spectroscopy, etc.

For this option in the delivery is included additionally:
LEMO-connection cable
LEMO-BNC adapter